1. Field of the Invention
The present invention relates to a package structure for an image sensor module, and more particularly to a package structure for an image sensor module with a three-dimensional die-stacking structure.
2. Description of the Related Art
Image sensors have been widely applied to electronic devices like camera cell phones, digital cameras, and devices associated with medical diagnoses or security monitoring. There are always needs on the market for thinner and more compact devices wherein energy loss can be reduced and production cost can be lowered, especially when portable electronic devices or medical instruments are considered. There are several known types of package structure for an image sensor: FIG. 11A of U.S. Pat. No. 6,646,289 discloses a wafer-level package structure for an image sensor, which employs a redistributed layer to redistribute electrical connections from the edge to the backside surface of individual dies. The image sensor therein is sandwiched between two layers of glass. FIG. 3 of U.S. Pat. No. 5,051,802 discloses an image sensor which is thinned to an extremely minute thickness so that a die is transparent to light rays from the backside thereof. FIG. 1 of U.S. Pat. No. 7,061,106 discloses an image sensor module using an interposer to achieve electrical connections between an image sensor and another die; moreover, a lens component is disposed unto a top of the interposer. FIG. 2 of U.S. Pat. No. 6,429,036 discloses an image sensor, a protective upper substrate of which is drilled to form electrical conduction vias so that the circuits can extend out board. Electrical connections are then made between the protective upper substrate and the image sensor by connecting them with solder balls or with a metal layer.
As described above, a conventional package structure for an image sensor typically employs a two-dimensional die-stacking structure and connection, which results in a greater electrical connection length and a larger package size; therefore, conventional structures will not be able to meet the needs of future products that take compactness, energy efficiency and high performance as basic elements. If a two-dimensional distribution of electrical connections within a die is changed to a three-dimensional one, the technical flaws of a conventional two-dimensional package structure may be overcome.